1. Field of the Invention
This invention generally relates to elevator systems. More particularly, this invention relates to a roller guide device for use in an elevator system.
2. Description of the Prior Art
Elevator systems are well known. A cab typically is guided within a hoistway along guide rails that extend vertically within the hoistway. Various configurations of guiding arrangements have been developed to provide smooth movement of the cab along the guide rails.
Typical guiding arrangements include rollers that roll along corresponding surfaces on a nose of the guide rail. One challenge facing designers of such devices is to provide for appropriate tolerances in the spacing of the rollers so that smooth movement of the cab is achieved by appropriate cooperation between the rollers and the guide rail nose surfaces. Manufacturing tolerances and variations in the surfaces on the guide rails make it difficult to have one roller guide device design be readily incorporated into a variety of elevator systems.
Another concern is maintaining contact between the guide rail and the rollers under the elevator operating conditions. For example, the cab may shift during travel because of weight shifts within the cab or other forces tending to move the cab laterally.
One approach is shown in U.S. Pat. No. 6,345,698. In that patent, two rollers are independently spring mounted such that the rollers are biased into engagement with the nose of a guide rail.
There is always a need for an improved arrangement. This invention provides a unique, self-centering roller guide arrangement.